1. Field of the Invention
The present invention relates to a vacuum exhaust mechanism, a compound type vacuum pump, and a rotating body part. More specifically, the present invention relates to a vacuum exhaust mechanism, a compound type vacuum pump, and a rotatoring body part that are capable of effectively connecting pipe lines having exhaust actions in a vacuum pump to be disposed.
2. Description of the Related Art
The vacuum pump according to the present invention has a casing that configures a housing having an inlet port and an outlet port, in which a structure that brings out the exhaust function of the vacuum pump is stored in this casing. This structure bringing out the exhaust function is configured mainly with a rotating portion (rotor portion) that is axially supported rotatably and a stator portion fixed to the casing.
The vacuum pump is also provided with a motor for rotating a rotating shaft at high speeds. By causing the motor to rotate the rotating shaft at high speed, gas is suctioned through the inlet port and discharged through the outlet port by the interaction between rotor blades (rotating discs) and stator blades (stator discs).
Of vacuum pumps, a Siegbahn type molecular pump with a Siegbahn type configuration has rotating discs (rotating circular plates) and stator discs arranged with a gap (clearance) with the rotating discs in an axial direction, wherein a spiral-shaped groove (helical groove or coil-shaped groove) flow channel is formed on the surface of at least each rotating disc or stator disc that is opposite to the gap. In this vacuum pump, the gas molecules spreading inside the spiral-shaped groove flow channel are given a momentum in a rotating disc tangential direction (i.e., the direction of the tangent to the direction of rotation of the rotating discs) by the rotating discs, and thereby evacuated with advantageous directivity through the spiral-shaped grooves from the inlet port toward the outlet port.
In order to industrially apply such Siegbahn type molecular pump or a vacuum pump having a Siegbahn type molecular pump portion, the rotating discs and the stator disc are arranged in multiple stages because with single stages of a rotating disc and a stator disc the compression ratio becomes insufficient.
The Siegbahn type molecular pump is a radial flow pump element. Therefore, in order to arrange the discs in multiple stages, a configuration is necessary in which, for example, the gas turns at the outer peripheral end portions and the inner peripheral end portions of the rotating discs and stator disc so as to be evacuated from the inlet port to the outlet port (i.e., along the axial direction of the vacuum pump), such as from the outer peripheral portion to the inner peripheral portion, then from the inner peripheral portion to the outer peripheral portion, and then again from the outer peripheral portion to the inner peripheral portion.
Japanese Patent Application Laid-open No. S60-204997 discloses a vacuum pump that has, in a pump housing, a turbomolecular pump portion, a spiral-shaped groove pump portion, and a centrifugal pump portion.
Japanese Utility Model Registration No. 2501275 discloses a Siegbahn type molecular pump in which spiral-shaped grooves extending in different directions are provided on a surface of each rotating disc and a surface of each stationary disc that are opposed each other.
The flow of gas molecules (gas) in the configuration described in each of these conventional technologies is as follows.
The gas molecules that are transferred to the inner diameter portion of an upstream Siegbahn type molecular pump portion are discharged to a space formed between a rotating cylinder and a stator disc. The gas molecules are then suctioned into the inner diameter portion of a downstream Siegbahn type molecular pump portion that is opened to the space, and then transferred to the outer diameter portion of the downstream Siegbahn type molecular pump portion. In a case where the discs are arranged in multiple stages, this flow of gas repeats throughout the stages.
However, since the exhaust does not act in the space described above (i.e., the space formed between the rotating cylinder and each stator disc), the momentum in the exhaust direction that is given to the gas molecules in the upstream Siegbahn type molecular pump portion is lost as soon as the gas molecules reach this space.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.